Contactless vital signs monitoring based on few-mode and multi-core fibers

Fengze Tan,Changyuan Yu,Shuyang Chen,Zhengyong Liu,Weimin Lyu

doi:10.29026/oea.2020.190034

Abstract

Few-mode and multi-core fibers are proposed and demonstrated for contactless vital signs monitoring in this paper. In-line optical fiber interferometers using few-mode and multi-core fibers are designed and offset splicing is utilized for mode excitation. Extinction ratio and insertion loss are analyzed experimentally under different offset distances. The fabricated in-line interferometers are packaged under the mattress to realize contactless vital signs signals collection. By using filtering techniques, both respiration and heartbeat signals can be recovered successfully, and respiration as well as heartbeat ratio are obtained. Mode excitation and interference are theoretically analyzed in few-mode fiber while curvature sensing experiments using multi-core fiber interferometer are performed to verify its excellent performance on vital signs monitoring. The successful demonstration on contactless vital signs monitoring makes few-mode and multi-core fibers promising candidates for healthcare applications.

Highlights

Vital signs, such as body temperature, respiration, heartbeat, blood pressure and pulse oxygenation, act as main health indicators of human body functions and the monitoring of vital signs becomes more and more important with the increasing concern on personal health condition among the public[1]
It can be seen that, both heartbeat rate (HR) and respiration rate (RR) results locate in the normal range and the interval errors are small enough to guarantee the accuracy for HR and RR estimation, which demonstrates the feasibility of few-mode fiber (FMF) and multi-core fiber (MCF) in-line interferometers for simultaneous as well as accurate vital signs monitoring in the contactless manner
FMF and MCF based in-line interferometers are proposed for contactless vital signs monitoring, including HR and RR

Summary

Introduction

Vital signs, such as body temperature, respiration, heartbeat, blood pressure and pulse oxygenation, act as main health indicators of human body functions and the monitoring of vital signs becomes more and more important with the increasing concern on personal health condition among the public[1]. In MCF and FMF, interference always happens among cores and modes, which can be utilized for sensing as in-line interferometers[31] These interferometers own the advantages of easy-fabrication, low-cost, high sensitivity, stability and compact, which can be promising candidates for contactless vital signs monitoring[32,33,34]. The models of FMF are established, including TMF and four-mode fiber, offset distance between cores in SMF and FMF is tuned and the excitation results of every mode can be obtained from the monitor set on the output end of FMF. The vital signs monitoring system can work with the same performance under other wavelengths considering the periodicity of the spectra shown above

Results

Discussion

Conclusions